High postoperative portal venous flow pulsatility indicates right ventricular dysfunction and predicts complications in cardiac surgery patients.

BACKGROUND: Right ventricular failure after cardiac surgery is associated with morbidity and mortality. Right ventricular dysfunction results in hepatic venous congestion, which impacts the portal circulation. We aimed to determine whether an increased portal flow pulsatility fraction was associated with right ventricular dysfunction in cardiac surgery patients. We also aimed to describe the haemodynamic factors and postoperative complications associated with an increased portal pulsatility in this setting. METHODS: We conducted a prospective single-centre cohort study, recruiting adults undergoing cardiac surgery. Portal flow was assessed before, during, and after surgery by Doppler ultrasound. A detailed haemodynamic and echocardiographic assessment was performed at the same time points. RESULTS: A total of 115 patients were included. Both systolic and diastolic right ventricular dysfunction were associated with a higher portal pulsatility fraction (P=0.008 and <0.001, respectively). A positive association was present between portal pulsatility fraction and measurements representative of venous pressure (central venous pressure, inferior vena cava diameter). A post-procedural portal pulsatility fraction ≥50% measured in the operating room was present in 21 (18.3%) patients and was associated with an increased risk of major complications (odds ratio=5.83, confidence interval, 2.04-16.68, P=0.001). The addition of portal flow assessment to a predictive model including EuroSCORE II and systolic right ventricular dysfunction improved prediction of postoperative complications. CONCLUSIONS: High portal flow pulsatility fraction is associated with right ventricular dysfunction, signs of venous congestion and decreased perfusion, and an increased risk of major complications. Portal vein Doppler ultrasound appears to be promising for risk assessment in the perioperative period. CLINICAL TRIALS REGISTRATION: NCT02658006.

Inhaled but not intravenous milrinone prevents pulmonary endothelial dysfunction after cardiopulmonary bypass.

OBJECTIVE: Cardiopulmonary bypass triggers a systemic inflammatory response that alters pulmonary endothelial function, which can contribute to pulmonary hypertension. Milrinone is a type III phosphodiesterase inhibitor. The objective of this study was to compare the effects of inhaled and intravenous milrinone on the pulmonary endothelium-dependent relaxations and hemodynamic and oxygenation parameters after cardiopulmonary bypass in a porcine model. METHODS: Five groups of Landrace swine were compared: (1) control group, no cardiopulmonary bypass; (2) bypass group, 90 minutes of normothermic bypass and 60 minutes of reperfusion; (3) inhaled milrinone group, bypass preceded by a 1.8-mg bolus of inhaled milrinone followed by a continuous milrinone nebulization; (4) intravenous milrinone group, bypass preceded by 2 mg of intravenous milrinone; and (5) inhaled NaCl group, bypass preceded by inhaled saline solution. After sacrifice, pulmonary arterial endothelium-dependent relaxations to acetylcholine and bradykinin were studied in organ chambers. RESULTS: Inhaled milrinone caused less hypotension ( P < .05), a lesser decrease in peripheral vascular resistances ( P < .01), and a lower heart rate ( P < .05) than intravenous milrinone. Inhaled milrinone prevented the alterations in relaxations of pulmonary arteries to acetylcholine caused by cardiopulmonary bypass, and relaxations to bradykinin were improved in the inhaled milrinone group ( P < .05) compared with the cardiopulmonary bypass and control groups. CONCLUSIONS: Inhaled milrinone prevents the occurrence of the pulmonary endothelial dysfunction seen after cardiopulmonary bypass. The hemodynamic and oxygenation profiles obtained with inhaled milrinone are safer than with intravenous milrinone. These strategies might be useful in preventing pulmonary hypertension after cardiac surgery.

Inhaled prostacyclin reduces cardiopulmonary bypass-induced pulmonary endothelial dysfunction via increased cyclic adenosine monophosphate levels.

OBJECTIVE: Cardiopulmonary bypass triggers a systemic inflammatory response that alters pulmonary endothelial function, which can contribute to pulmonary hypertension. This study was designed to demonstrate that inhaled prostacyclin, a selective pulmonary vasodilator prostaglandin, prevents pulmonary arterial endothelial dysfunction induced by cardiopulmonary bypass. METHODS: Three groups of Landrace swine were compared: control without cardiopulmonary bypass (control group); 90 minutes of normothermic cardiopulmonary bypass (bypass group); 90 minutes of cardiopulmonary bypass and treated with prostacyclin during cardiopulmonary bypass (continuous nebulization with continuous positive airway pressure until the end of the cardiopulmonary bypass; prostacyclin group). After 60 minutes of reperfusion, swine were put to death and pulmonary arteries harvested. After contraction to phenylephrine, endothelium-dependent relaxation to bradykinin and acetylcholine was studied in standard organ chamber experiments. The pulmonary artery intravascular cyclic adenosine monophosphate content was compared between the 3 groups (post-cardiopulmonary bypass). RESULTS: There was a statistically significant improvement of the endothelium-dependent relaxation to bradykinin in the prostacyclin group when compared with the bypass group (P <.05). There was no statistically significant difference for endothelium-dependent relaxation to acetylcholine (P >.05) between the prostacyclin and the bypass groups. There was a statistically significant decrease in the cyclic adenosine monophosphate content and a statistically significant increase of the mean pulmonary artery pressure in the bypass group only (P <.05). CONCLUSION: Prophylactic use of inhaled prostacyclin has a favorable impact on the pulmonary endothelial dysfunction induced by cardiopulmonary bypass associated with preservation of pulmonary intravascular cyclic adenosine monophosphate content and the pulmonary vascular tone.

EMLA partially relieves the pain of EMG needling.

The aim of this study was to evaluate the efficacy of the topical analgesic cream EMLA in alleviating the pains caused by needling in electromyography (EMG). During the course of regular neurophysiology clinics, 34 Caucasian patients of both sexes, aged 21 to 69 yr (mean 38.5 +/- 11.4 SD), scheduled for electromyography, were studied. The EMLA was spread thickly on two EMG sites on each arm: E site, on the lateral dorsal aspect of the forearm and A site, on the thenar eminence. Randomization was pre-established. Whenever EMLA was applied blindly on one of the sites of the arm, the placebo was applied on the homologous site of the other arm. After at least 45 min of application (range 45-145 min, mean = 72.3 +/- 22.2), the needle was inserted into the skin and into the muscle. Then the electromyographist asked the patient to score his degree of pain on a visual analogue scale (VAS 1-10 cm) for each level of insertion. The results showed that on the skin of E site, the pain was less after EMLA than placebo (VAS = 0.75 +/- 1.36 vs 3.10 +/- 1.75, P = 0.0001). The untreated E site (placebo) was less sensitive than the untreated A site (VAS = 3.10 +/- 1.75 vs 6.09 +/- 1.96, P = 0.0001). Muscle insertion on E site was less painful on the EMLA sites than placebo (VAS = 2.83 +/- 2.45 vs 5.73 +/- 2.30, P = 0.0001). The VAS scores for skin and muscle insertion on A site were identical whether EMLA or placebo had been applied.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of lidocaine hydrocarbonate, lidocaine hydrochloride and mepivacaine in the axillary block.

Axillary block was performed on 60 patients undergoing various types of surgical procedures on the upper limb. The patients were divided randomly into three equal groups of 20 and received lidocaine hydrocarbonate 1% or lidocaine hydrochloride 1% or mepivacaine 1%, each solution containing epinephrine 1/400,000. A double-blind design was used. Lidocaine hydrocarbonate and lidocaine hydrochloride were both found to have a shorter latency of analgesia than mepivacaine. Duration of analgesia, quality of the sensory and motor block were not found to be statistically different between the three groups.

Oscillometry and direct blood pressure: a comparative clinical study during deliberate hypotension.

Oscillometry using an automatic monitor was compared with invasive blood pressure monitoring in 21 patients scheduled for surgery under general anaesthesia with deliberate hypotension. Six ranges of mean blood pressure measurements were studied, two of which were hypotensive. An excellent correlation was found between the two methods (systolic: r = 0.94; mean: r = 0.93; diastolic: r = 0.88) but there was a large variability among individual subjects. For systolic, diastolic and mean intra-arterial readings above an approximative value of 10.64 KPa (80 mmHg), the oscillometric monitor was found to underestimate blood pressure. Inversely, it was found to overestimate blood pressure for intra-arterial readings under the approximative value of 10.8 KPa (80 mmHg). We conclude that the non-invasive monitor represents a good trend estimation of the invasive radial blood pressure technique, but that wide inter-individual variability and the overestimation of blood pressure below an approximative value of 10.64 KPa (80 mmHg) precludes interchange of techniques when absolute values are considered, especially during controlled hypotension. However, oscillometry could represent a better estimate of central aortic pressure.

The sleep apnoea syndrome and epidural morphine.

A patient not known in advance to have the sleep apnoea syndrome (SAS) was administered a combined epidural-general anaesthetic for a proposed radical prostatectomy. After surgery which had to be discontinued due to extensive tumoural spread, morphine 5 mg was administered through the epidural catheter for analgesia. Severe respiratory depression occurred eight hours later and was successfully reversed by repeated injections of naloxone. The potential danger of epidural morphine administration to SAS patients is discussed.

Effects of carbon dioxide and epinephrine on serum levels of lidocaine after epidural anaesthesia.

Carbonated lidocaine is believed to penetrate membranes more rapidly than its hydrochloride salt and could possibly cause higher serum levels. To compare serum levels, arterial blood samples drawn at intervals were analyzed in a group of 18 patients under epidural anaesthesia with equivalent doses of lidocaine hydrochloride and lidocaine hydrocarbonate, with and without epinephrine. Results show that serum levels were significantly higher when lidocaine hydrocarbonate was used for epidural analgesia.

Comparison of the clinical effectiveness of lidocaine hydrocarbonate and lidocaine hydrochloride with and without epinephrine in epidural anaesthesia.

Epidural analgesia was administered to one hundred patients undergoing various types of surgical procedures. They were divided at random into four equal groups who received lidocaine hydrocarbonate or lidocaine hydrochloride, both with or without epinephrine. A double blind method was used. The study was designed first to test the validity of claims that lidocaine hydrocarbonate produces a shorter period of onset for effective analgesia, a more profound sensory and motor block, and a higher spread of analgesia than the hydrochloride salt and secondly, to identify the respective roles of carbon dioxide and epinephrine in obtaining this alleged superior effectiveness. The results of the study showed that carbon dioxide improved the quality of sensory block, but we could not find any significant difference between lidocaine hydrocarbonate and lidocaine hydrochloride salt, with and without epinephrine, with regard to rapidity of onset, upward spread of analgesia and quality of motor block. As was already known, duration of analgesia was prolonged by the addition of epinephrine but not by the addition of carbon dioxide. They study also showed that the compliance of the epidural space was decreased in the lidocaine hydrocarbonate groups compared to those with lidocaine hydrochloride. There is a positive correlation between the duration of sensory block or the upper level of analgesia and compliance in the hundred patients studied. It is concluded that the hydrocarbonate base, because of its more profound sensory block in the L5-S1 segment, can be useful for operations on the lower extremities, especially in the L5-S1 segmental distribution. However, knowing that the hydrocarbonate base is more expensive, one must use his own judgment in appraising the cost-benefit of its use.

[Use of frozen hypertonic saline in the treatment of pain]. / Utilisation de solute froid hypertonique dans le traitement de la douleur.

Fifteen cases of patients referred for treatment of acute and chronic pain problems are reported. The results show that both epidural and peripheric hypertonic frozen saline 5 p. 100 injections were effective, as far as three months afterwards. The possible mechanism of action of frozen saline is discussed.

Nitroprusside, its metabolites and red cell function.

The effects on metabolism and red cell function of blood levels of thiocyanate (SCN-) and cyanide (CN-) were studied in 42 patients undergoing surgery under controlled hypotension (CH) induced by sodium nitroprusside (SNP). The mean dosage of SNP administered was 21.38 mg (SD = 12). The durating of perfusion was 121 minutes (SD = 11). All operations were performed under neuroleptanalgesia without complications. No tachyphylaxis was encountered. Under SNP a slight increase of blood SCN- (from 13.9 mg/l +/- 1.1 to 23 mg/l +/- 2.6) was found. Blood levels of CN- are increased mostly in the red cell, the mean value being 0.300 mg/l +/- 0.10 for whole blood after two hours of perfusion. This value decreased when perfusion was stopped. All blood samples were negative for methaemoglobin and cyanmethaemoglobin. Carbonic anhydrase activity was not modified, CN- toxicity levels for this enzyme being 50 times higher than those found during our study. 2,3-DPG levels did not vary. Blood gases, acid-base balance and Davo2 did not change significantly, although a slight increase in blood lactate was measured. As shown by this study, appreciable amounts of CN- are detected in blood during SNP perfusion while SCN- stays at relatively low levels. Fortunately most of the CN- released from SNP moves into the red cell and does not alter its functions at clinical concentrations. The low plasma concentration of CN- is not sufficient to cause important metabolic disturbances. However, dosages of SNP higher than those administered during this study could increase the blood and tissue CN- to toxic levels. A toxicity study shows that, during a relatively short period of time, SNP dosage should not exceed 1.16 mg/kg or a maximum of 10 microgram/kg/min for a period of two hours.